Receiver for telephones.



G. N. BLANGHARD & O. G. MINZENMAYER.

RECEIVER FOR TELEPHONES.

APPLICATION FILED JULY 10,1912.

- phone receivers,

enonen 1v. BLANCHARD annor'ro e. MlNZENMAYERQf SAN FRANCISCO, caL-rromvra.

RECEIVER FOR TELEPHONES.

Specification of Letters Patent.

Patented Jury 211. ram.

Application filed July 10, 1912. Serial No. 708,569.

To all whom it may concern:

Be it known. that we, GEORGE N. ELAN-- CHARD and OTTO G. MINZENMAYER, citizens of the United States, residing in the city and county of San Francisco and State of Cali-.

fornia, have invented certain new and useful Improvements in Receivers for Telephones, of which the following is a specification.

The hereinafter described invention relates to an improvement for increasing the intensity of the sound reproduction of telemore especially those employing a horn for enlarging the volume of sound, and the object of the invention is to distinctly reproduce sounds and articulate speech sufficiently loud to be heard at a considerable distance by the attachment of a megaphone or horn to the receiver.

In receivers as ordinarily constructed, whether of single or double pole, the iron diaphragm acts as the armature for the magnet, which answers fairly well with the feeble current and consequent feeble magnetic effect induced in the receiver, but when more powerful results are desired it becomes necessary to have a path for the magnetic flux of greater cross section than the thin iron diaphragm affords.

. To comprehend the invention, reference should be had to the accompanying sheet of drawings, wherein- Figure 1 is a longitudinal sectional view of the improved receiver. Fig. 2 is an enlarged detail view of the magnet cores and the armature which coacts therewith.

In the drawings, the numeral 1 is used to indicate a suitable casing, preferably cylindrical in cross section and containing a mica or other non-magnetic diaphragm 2, which diaphragm'is clamped or held at its periphery between two rubber. washers 3 and 3 in any suitable manner, as by'means of a threaded ring 4: which screws into the casing 1.

To the under face of the diaphragm 2 and centrally thereof is secured a wedge shapediron armature 5, which in the present case isheld to the diaphragm by a screw 6. This armature co-acts with two soft iron cores 7 and 7,.which cores are secured in any suitable manner to the poles 'of a magnet 8, and the said cores are wound with the insulated wires 9.

The polar faces 9 of the cores 7 and 7' of the ma net 8 are shaped to conformto. the sides of t e wedge shaped armature 5, and

by reason of such construction of the polar faces of the-cores 7 and 7 and the armature 5 it is possible to have ample cross section to carry the magnetic flux with a minimum weight, inasmuch as the armature, being in the shortest path which the magnetic flux can-take, can be made exceedingly narrow and consequently very light in weight without undue magnetic leakage, the lightness of the armature being an important factor where the rate of vibration is high. Again, as the magnetic pull is at rig-ht angles to the armature sides, and as'ythese sides are not parallel with the diaphragm,-it is evident that the pull on the diaphragm is less than where the polar faces are parallel to the armature.

The strain on the diaphragm can be reduced to the proper degree by making the armature and the polar faces of the cores of pro-per angle relative to each other, and inasmuch as the air gaps are not parallel with the diaphragm, they are subject to less change in length of any given amplitude of vibration than when parallel with the diaphragm. v

The magnet 8 with its cores? and Tis adjustably supported from the casing I by any suitable means, as by the hangers 10, which are slotted at their lower ends to receive the set screws 11 for securing the mag-- net 8 thereto and holdingthe same in adjusted position. By thus giving adjustability to the magnet 8, the same may be so regulated as to place the wedge shaped armature 5 in very close proximity to the polar faces of the cores 7 and 7 without actually coming in contact therewith.

To the casing 1 is secured a horn or megaphone 12, through which the sounds reproduced by the receiver issue. 11.

By means of the wedge shaped armature I ing to the sides of the armature, the magnetic circuit is completed through iron and steel, excepting for the two air gaps, which have been shown to be exceedingly small, Without the necessity of employing or using an iron diaphragm.

The Working parts of the instrument are inclosed or housed Within an ordinary outer shell 12- to which the casing 1 carrying the diaphragm 2 and armature 5 is secured, the said outer shell or housing being constructed of suitable material.

Theinstrument as constructed consists of but few parts, and as a whole the same is compact and rigid.

Having thus described the invention what is claimed as new, and desired to protect by -Letters Patent is Ina receiver for the described purpose, the combination with a housing open at one end, a disleshaped hanger threaded into the. open end of said housing and formed centrally with an opening, a bell mouth cover .and extending over the opening in said hanger, a Wedge shaped armature detachably carried by the under surface of said diaphragm, and cores carried by said mag-' not and extending through the opening 111 said hanger, the polar faces of which are shaped to conform to the side of the armature.

In testimony whereof: We have signed our names'to this specification in the presence of tWo subscribing Witnesses.

' GEORGE N. BLAXCHARD. OTTO G. MlNZENMAYER.

Witnesses: I

N. A. ACKER, D. B. RICHARDS. 

